Use of waste carpet as filler

ABSTRACT

By utilizing specially processed waste carpeting as a filler in the production of carpet backcoating, roofing materials, or other similar products, the amount of waste carpeting that is landfilled or otherwise disposed of is significantly reduced as is the need for mining the mineral fillers. Waste carpeting (post-consumer and/or waste from new carpet manufacture) containing calcium carbonate and a thermoplastic resin is collected and size-reduced to a size corresponding to the size of calcium carbonate typically used as a filler. The size-reduced waste carpeting is added as filler to at least one other material, such as polymers in standard latex, EVA, or PVC carpet backcoatings, to provide a composite used in the manufacture of a useful product (like carpet backcoating), and then the composite material is used to make the useful product (such as carpet backcoating, which is used as a primary or secondary backcoating in the manufacture of new carpeting). The waste carpeting may provide between 0-100% of the filler of carpet backcoating, with any remainder made up by conventional fillers, such as calcium carbonate.

BACKGROUND AND SUMMARY OF THE INVENTION

In the conventional manufacture of carpeting, tufted pile yarns or likefacings are held in place by a primary backing, and typically asecondary backing—as well as possibly other layers—also associated withthe carpeting. At least some of the carpet backings (particularly latex,EVA, PVC, or other polymer-based backings) use filler as an importantcomponent thereof. The standard filler that is used is a mineral filler,typically calcium carbonate, alone, or in combination with some othermaterials

During the carpet manufacturing process there is waste carpetingproduced, which is typically landfilled or burned. When new carpets areinstalled in place of old carpeting, the used, waste carpeting (which ispost-consumer waste at that point) is ripped up and also typicallylandfilled or burned. The calcium carbonate, or like mineral fillers,that are used in carpet backings are mined, and therefore haveassociated therewith the conventional problems associated with themining of materials. In certain waste carpeting materials, othermaterials, such as thermoplastic resins, form constituent parts of thewaste material together with the calcium carbonate filler and arerecoverable.

According to the present invention, methods of recycling wastecarpeting, including calcium carbonate and thermoplastic resinmaterials, and carpeting produced utilizing such recycled materials, areprovided which substantially eliminate or significantly reduce theproblems discussed above. According to the present invention instead ofusing calcium carbonate, which is mined, as the filler for a carpetbacking, recycled waste carpet containing calcium carbonate as well as athermoplastic resin (from new carpet production and/or frompost-consumer waste) is used as a filler material. The recycled materialmay also be used in conjunction with fresh calcium carbonate, e.g.,freshly mined, as well as fresh thermoplastic resin. This substantiallyeliminates, or at least significantly reduces, the amount of landfillingor other waste disposal that is necessary for waste carpeting.

While the invention is particularly useful for recycling waste carpet inthe manufacture of new carpeting, the invention is also applicable tothe production of other materials containing fillers, including variousextruded thermoplastic and thermoset materials that typically usecalcium carbonate filler, including, but not limited to, roofingmaterials, road paving materials, awnings, and tarps.

According to one aspect of the present invention there is provided amethod of recycling waste carpeting comprising substantiallysequentially: (a) collecting waste carpeting; (b) processing the wastecarpeting to provide a first material from the waste carpetingcontaining a filler and a thermoplastic resin; (c) adding the firstmaterial to a second material to provide a composite material useful inthe manufacture of a useful product; and (d) making the useful productusing the composite material.

In the method, step (a) may be practiced to collect substantially onlypost-consumer waste carpeting, substantially only waste carpeting fromnew carpeting manufacture, or a blend of both. Post-consumer wastecarpeting can be cleaned by any conventional cleaning technique beforeuse, if desired or necessary. While the method is typically practicedutilizing all of the face yarn and primary backing, and backcoatings,under some circumstances the method may further comprise, as part ofstep (b), separating the face yarn and primary backing from wastecarpeting backcoating to produce a substantially face yarn and primarybacking-free waste carpeting backcoating, and using substantially onlythe waste carpeting backcoating. Also, various carpet backcoatings maybe separated from each other so as to use only one particular carpetbackcoating, such as the primary or secondary backcoating.

The invention also as part of step (b) includes reducing the firstmaterial to a predetermined size in a range of 50-100 to 95-325 whereinthe first number represents the percentage of the first material whichwill pass through a mesh screen having a mesh size corresponding to thesecond number. Also, step (c) may include adding the first material tothe second material to form a carpet backcoating and step (d) ispracticed by making a carpet backcoating. Additionally, the compositematerial of step (c) may be processed in molten form to have a viscosityin the range of 10,000 to 30,000 CPS. The latter viscosity range isparticularly used for forming a primary backcoating for carpeting. Inone embodiment of the useful product formed hereby, the carpet productmay have a backcoating with about 3-30% EVA copolymer, about 32-45%resin and 50% filler wherein the filler comprises calcium carbonate anda predetermined percentage of the composite material.

In another embodiment hereof, the method may be practiced employingsteps (a) and (b) above, and in lieu of steps (c) and (d), (c) heatingthe first material to a temperature enabling the first material to flowand (d) flowing the first material onto a second material to bond thefirst and second materials to one another to form a useful product.Thus, the waste carpet material when in flowable form may be placed forexample on the backside of fiberglass carpet tile where the materialbonds to itself and to the fiberglass when subjected to heat.

It will be appreciated that the method hereof is useful to form carpetbackcoatings comprised of EVA or PVC or other polymer base backcoatings.The invention also further typically comprises making new carpeting withthe carpet backcoating. Additionally, the method hereof is useful toform carpet backcoatings comprised of SBR latex compounds wherein therecycled calcium carbonate filler may be used in lieu of or incombination with fresh calcium carbonate to form the carpet backcoatingin conjunction with other materials. Further, the composite material maybe used to produce extruded thermoplastic or thermoset products.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of conventional carpeting, orcarpeting produced according to the present invention; and

FIG. 2 is a block diagram illustrating various method procedures thatmay be practiced according to the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

A standard construction of carpeting is illustrated schematically byreference numeral 10 in FIG. 1. The carpeting includes face yarn 11,tufted into a woven or spun bonded fabric 14 known as a primary backing.The primary backing 14 has pile yarns 11 tufted therethrough extendingoutwardly from one face, a primary backcoating or precoat 12 on theopposite face, and at least one secondary backcoating or main coat 13.Other layers may also be associated with the carpeting 10. The primarybackcoating or precoat 12 typically comprises latex, PVC(polyvinylchloride), EVA (ethylene vinyl acetate), or otherpolymer-based material, and the secondary backcoating 13 may alsocomprise or include polymers. Typically one or both of the primarybackcoatings 12 and secondary backcoating(s) 13 include filler. The mostcommon filler is mineral filler, typically calcium carbonate, althoughother fillers may be utilized, or calcium carbonate can be used withother common materials such as metal salts. According to the invention,carpeting 10 may be produced with the filler of one or both of theprimary backcoating 12 and secondary backcoating(s) 13 comprising wastecarpeting instead of calcium carbonate as all or part of the filler.

The carpeting 10 may also have any number of other layers, dependingupon use. For example the carpeting 10 may have a conventional secondarybacking (typically a woven or needle punched fabric adapted to contactthe floor or padding).

FIG. 2 schematically illustrates an exemplary process according to thepresent invention. In the process, used carpeting is initially collectedas indicated at 20 in FIG. 2. The collection may comprise post-consumerwaste carpeting, waste carpeting from the standard procedures associatedwith the manufacture of new carpeting, or both. If the used carpetingcollected at 20 is contaminated in any significant manner it may becleaned using any suitable conventional technique (either before orafter size-reduction as hereinafter described).

It is contemplated that according to the present invention the wastecarpeting that is subsequently employed in the practice of the inventionis substantially all components of waste carpeting, including the faceyarns, primary backing, and primary and secondary backcoatings, andperhaps other components. However under some circumstances for eitherpart or all of the waste carpeting it may be desirable to separate theface and primary backing and backcoatings from each other before furtherprocedures. The optional separation of the carpet components isillustrated schematically at 21 in FIG. 2. The separation may beaccomplished, depending upon whether the face and all backings andbackcoatings are to be separated, utilizing any suitable conventionaltechnique, such as generally described in U.S. Pat. No. 5,728,741 (thedisclosure of which is hereby incorporated by reference herein). If onlya certain backing or backcoating is used, an attempt may be made tomatch it with the manufacture of new backing or backcoating ofsubstantially the same type (e.g., latex backcoating).

While a number of different types of waste carpet material may be used,it has been found particularly beneficial to process waste carpetinghaving as constituent components calcium carbonate and a thermoplasticresin mixture. One such waste carpet material is known as Co-Product(Residue from Carpet Recycling Process) manufactured by Evergreen NylonRecycling LLC, a joint venture of DSM and Honeywell in Augusta, Ga. inwhich the waste carpet material includes calcium carbonate 50-70%, athermoplastic resin mixture 0-45%, nylon 0-45% and caprolactam 0-8%, allpercentages being by weight. Other trace materials may also appear inthe waste material. This material is particularly useful as part or allof the filler for a backcoating for use in carpet manufacture comprisedof 3-30% EVA copolymer; 15-65% resin, such as ECR-171 from Exxon; and30-70% calcium carbonate filler, JR-78, all percentages again being byweight. It is believed these waste product materials are particularlybeneficial because at normal temperatures for forming the carpetbackcoating under the preceding formula, the waste carpet material hastemperature, flowability and viscosity parameters substantiallycorresponding with the standard backcoating according to that formula.

Turning back to FIG. 2, whether or not the proper components areseparated, the waste carpet material comprising the calcium carbonateand the thermoplastic resin are reduced in size to a particular sizecorresponding to a filler size used to produce the backcoating forcarpeting. Consequently, the carpet waste material is reduced in size,preferably ground, to a typical grind useful for resin and latex basedcompounds for use in backcoating of carpet. This grinding can beachieved with conventional machinery used in the filler trade such as aRaymond Roller Mill or an Imp Mill. Although not necessary with thematerial described, cryogenic grinding could also be used. No specialequipment is needed for grinding the waste carpet material. The groundparticulate size has a range of 50-100 to 95-325 and particularly a78-200 grind is preferred (the first number represents the percentage ofthe material which will pass through a mesh screen having a mesh sizecorresponding to the second number). The particulate size of the wastecarpet material is significant in that it has been found that the samematerial in larger size when added to a molten resin caused foaming ofthe material which could lead to manufacturing problems. It was foundhowever that by grinding the material to a size correspondingsubstantially to the size of standard filler material used tomanufacture new carpet or by adding the larger size material before themolten resin, the foaming problem did not materialize. Consequently theground waste carpet material could be added as filler to other standardcarpeting backing components as indicated at 25 in drawing FIG. 2.

In the preferred procedure according to the present invention, theproperly sized waste carpeting may be used as a filler with otherstandard carpet backcoating components, either for primary backcoatingor a secondary backcoating or other backing elements of carpeting(typically collectively referred to as main coats). For example, theground waste carpet material may be used in conjunction with latex, EVA,or PVC backcoatings of conventional construction and may be usedsubstantially as the only filler material or can replace a significantamount of the filler material when combined with standard fresh fillermaterial.

It has also been found that the waste carpet material when ground andadded to molten resin used in the production of a main backcoating andheated to approximately 325° F. yielded a viscosity of the mix of about14,000 CPS. A viscosity within a range of 10,000-30,000 CPS isappropriate for the formation of a backcoating for carpeting inaccordance with the above formula. These temperatures and viscositiesare amenable for production in existing backcoating producing equipment.That is, the viscosity is significant inasmuch as the molten resin mustbe pumped to various machinery and also must flow at a certain rate on aapplicator roll or through a slot die or an extruder for disposition onthe back of the carpet at a predetermined thickness. It will beappreciated that the waste carpet material ground to appropriate sizemay be a substitute for all or a portion of fresh calcium carbonatefiller in the formation of a new carpeting product. Thus, once thebackcoating is formed from the carpet waste material as illustrated bybox 26 in FIG. 2, the flowable backcoating formed of recycled carpetwaste material in whole or in part is applied to the back of the carpetin a predetermined thickness as indicated at 27 in FIG. 2. That is, thewaste carpeting filler according to the present invention is mixed withthe other components using standard equipment and techniques and thenultimately new carpet backcoating is produced as indicated at 26 in FIG.2 again using conventional techniques. The new carpet backcoatingincorporating the waste carpet material may then be used to make the newcarpet again by conventional techniques as schematically illustrated at27 in FIG. 2. The backing from 26 may be used as the primary backcoating12 or a secondary backcoating 13 of the carpet or as filler in all ofthe backcoatings.

The ground material from 22 in FIG. 2 may also be added to a PVC maincoat to replace some of the normal or fresh calcium carbonate filler.PVC is used as a backing on most carpet tiles. Consequently, a processfor forming a typical mix for a PVC main coat may comprise: (a)collecting waste carpeting; (b) processing the waste carpeting toprovide a first material from the waste carpeting containing a fillerand a thermoplastic resin; (c) adding the first material to a secondmaterial to provide a composite material useful in the manufacture of auseful product; and, (d) making the useful product using the compositematerial.

Further, the waste carpet material when ground has a melting pointsufficient to render the material flowable at a certain temperature forexample 150° C. While the ground material does not completely meltbecause of the calcium carbonate content, the capacity of the materialto melt at reasonable temperatures enables the application of a layer ofthe material onto a fiberglass backing normally used to stabilize acarpet tile. Thus, by applying the material at temperature forflowability, the material bonds to itself and to the fiberglass backingof the carpet tile when heated.

Still further, the waste carpet material, when ground as indicatedabove, may also be used as a filler in SBR latex compounds usedthroughout the industry for laminating carpet. A typical formula forlatex compounds could be water, 5-20%; SBR latex, such as Reicholds68909. 20-40%; minor constituents such as foamers and stabilizers neededfor compounding, 1-5%; and a calcium carbonate filler from 0-70%. Thewaste carpet material of the present invention may be used in lieu ofthe calcium carbonate filler typically used in these latex compounds inthe same percentage, i.e., 0-70%. Thus, the waste carpet may entirelyreplace the fresh calcium carbonate filler typically used in whole or inpart, i.e., may be blended with the fresh calcium carbonate filler.Preferably, a significant amount of the calcium carbonate can bereplaced by the size-reduced waste carpeting. For example, about 40% ofthe filler of the carpet backcoating may be size-reduced wastecarpeting. In the above example, about 20-50% of the carpet backcoatingmay be size-reduced waste carpeting filler and about 0-30% calciumcarbonate filler, e.g., about 25% each of size-reduced waste carpetingand calcium carbonate as fillers.

It will be appreciated that the use of the waste carpet material hasapplications other than in the formation of new carpets or carpet tiles.For example, the waste carpeting may be added as a filler to othermaterials to make other useful products such as extruded thermoplasticor thermoset materials that can typically use calcium carbonate or othermineral fillers. A number of other products that may be made comprisealmost all products that typically can use calcium carbonate (or itsequivalent) as the filler and some of the new products that can be madeinclude roofing materials, awnings, road surfacing materials and tarpsas illustrated at 30 and 31 in FIG. 2, all of which contain mineralfillers. The reduction in size of the waste material may not be as smallas for carpet backcoatings for such other end products.

During any of the procedures described above, various conventionalrefinements may be employed. For example, screening or other contaminateremoval practices may be employed as desired to produce a product withthe desired properties.

As a consequence of this invention, it is possible to substantiallyeliminate or significantly reduce land filling or other disposal ofwaste carpeting and at the same time reduce the mining of mineralfillers without sacrificing product quality by using processed wastecarpeting as a filler for carpet backcoatings, roofing materials, andother products.

While the invention has been herein shown and described in what ispresently conceived to be the most practical and preferred embodimentthereof, it will be apparent to those of ordinary skill in the art thatmany modifications may be made thereof within the scope of theinvention, which scope is to be accorded the broadest interpretation ofthe appended claims so as to encompass all equivalent products andprocesses.

1-14. (Canceled)
 15. A method of recycling waste carpeting and forming anew carpet containing the recycled waste carpeting comprising: (a)collecting waste carpeting containing calcium carbonate andthermoplastic materials; (b) processing the waste carpeting to provide afirst material from the waste carpeting containing a first fillerincluding the calcium carbonate and the thermoplastic materials andreducing the first material to a predetermined size in a range of 50-100to 95-325 wherein the first number represents the percentage of thefirst material which will pass through a mesh screen having a mesh sizecorresponding to the second number; (c) adding the first material to asecond material to provide a composite material useful in themanufacture of the new carpet; and (d) making the new carpet containingthe composite material.
 16. A method according to claim 15 wherein step(b) includes reducing the first material to a predetermined size in arange of 50-100 to 95-325 wherein the first number represents thepercentage of the first material which will pass through a mesh screenhaving a mesh size corresponding to the second number.
 17. A methodaccording to claim 16 wherein the step of reducing includes grinding thefirst material.
 18. A method according to claim 15 wherein the fillercomprises calcium carbonate.
 19. A method according to claim 15including adding the first material to the second material to comprise acarpet backcoating and where step (c) is practiced by making a carpetbackcoating.
 20. A method according to claim 19 including processing thecomposite material of step (c) into molten form having a viscosity in arange of 10,000-30,000 CPS.
 21. A method according to claim 20 whereinstep (c) is practiced to produce a carpet backcoating with about 3-30%EVA copolymer, about 15-65% resin and 30-70% of a second filler whereinthe second filler comprises calcium carbonate and a predeterminedpercentage of the composite material.
 22. A method according to claim 15wherein steps (c) and (d) are practiced to produce thermoplastic orthermoset products.
 23. A method according to claim 15 wherein steps (c)and (d) are practiced to produce PVC products.
 24. A method of recyclingwaste carpeting comprising: (a) collecting waste carpeting; (b)processing the waste carpeting to provide a first material from thewaste carpeting containing a filler and thermoplastic materials: (c)heating the first material to a temperature enabling the first materialto flow; and (d) flowing the first material onto a second material tobond the first material and second material to one another to form auseful product.
 25. A method according to claim 24 wherein step (d)includes flowing the first material onto the second material wherein thesecond material is formed of fiberglass and making new carpeting withthe first and second materials and fiberglass.
 26. Carpeting having aface, primary backing, primary backcoating and at least one secondarybackcoating; and wherein at least one of said primary and secondarybackcoatings comprise a latex compound and a filler and wherein about20-50% of said filler is size-reduced waste carpeting.
 27. Carpetingaccording to claim 26 wherein said size-reduced waste carpetingcomprises size-reduced post-consumer waste carpeting and wherein saidfiller has a particle size in a range of about 50-100 to 95-325 whereinthe first number represents the percentage of the filler which will passthrough a mesh screen having a mesh size corresponding to the secondnumber.
 28. A method of recycling waste carpeting and forming a usefulintermediate product, comprising the steps of: (a) collecting wastecarpeting containing calcium carbonate and at least one of athermoplastic resin, nylon and caprolactam; and (b) reducing the wastecarpeting to a predetermined particle size in a range of 50-100 to95-325 wherein the first number represents the percentage of the wastecarpeting which pass through a mesh screen having a mesh sizecorresponding to the second number.
 29. A method according to claim 28wherein step (b) includes grinding the waste carpeting.
 30. A methodaccording to claim 28 wherein step (b) including grinding the wastecarpeting to produce particles having a particle size in a range ofabout 78-200.
 31. A method according to claim 28 wherein the wastecarpeting of step (a) contains calcium carbonate 50-70%, a thermoplasticresin mixture 0-45%, nylon 0-45% and caprolactam 0-8%, said percentagesbeing by weight.
 32. A method according to claim 28, includingprocessing the reduced waste carpeting to provide a final usefulproduct, the step of processing including combining the waste carpetingin a molten resin to form the useful process.